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Home: Perl Programming Help: Beginner:
"defined" in while loop



Feb 15, 2009, 2:23 PM

Post #1 of 1 (2194 views)
"defined" in while loop Can't Post

1) while(<stdin>){print " I saw $_" ;}

# Is thie equivalent to

2) while($_=<stdin>){ print "I saw $_" ;}

If it is so, , how will this code end after printing "I saw whateverentered"

As there is no "defined" used in while loop , so how will while loop end because undefined value in the $_ will not let the loop end.

3) while(defined($_= <stdin>)){print "I saw $_ " ;}

In either of these three codes, output is the same.

While I was going thru book, it is stated for the first code "Read a line of input and see if its true. And if its true, enter the while loop but throw away that line of input." What does this mean ? Does it mean that line of input will be read but not printed ? Why not ? Because by default any input will be assigned to $_.

Pls explain.

(This post was edited by jigneshjsoni on Feb 15, 2009, 2:33 PM)


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